Magnetic proximity switches, also known as limit switches, are commonly used for position sensing. Typically, magnetically-triggered proximity switches include a sensor that is adapted to detect the presence of a target without physically contacting the target. Typically, the sensor may include a switching circuit mechanism enclosed within a switch body, and the switching circuit mechanism typically includes multiple levers and contacts that are biased into a first position by one or more springs. When the target, which generally includes a permanent magnet contained within a housing, passes within a predetermined range of the sensor, the magnetic flux generated by the target magnet triggers the switching circuit mechanism, thereby closing a normally open circuit. The closing of the normally open circuit is detected by a processor, and a signal is sent to an operator or an automated operation system to indicate the presence of the target within the predetermined range of the sensor. The target is typically secured to a displaceable element of a system, such as a valve stem, and the sensor is typically secured to a stationary element of a system, such as a valve body. When so configured, the sensor can detect when the displaceable element has changed positions.
Typically, the sensor is disposed within or secured to a durable housing to protect the sensor. A connector socket assembly is coupled to the sensor housing (by a welding operation, for example) and the connector socket assembly includes a field side connector. However, due to the relatively large physical size of the sensor necessary to enclose the switching circuit mechanism, typical sensor housings are relatively large and cannot be used in applications requiring the placement of the sensor in an area having limited free space. In addition, the need to provide power to the sensor also limits the applications in which the sensor can be used.
While a relatively small magnetically-triggered proximity switch (and a correspondingly smaller housing) may be desirable, the ability to reduce the size of the proximity switch may be limited by several factors. Specifically, if relatively high load values are required in addition to programmable logic controller (“PLC”) level loads of about 5V, correspondingly large contacts are necessary to accommodate the greater loads, and these large contacts limit the ability of the switch to be reduced in size. Additionally, as previously explained, there are numerous components that are disposed within the switch housing, and the size of the relatively complex actuation assembly limits the minimum size of the switch. Such a complex actuation assembly also adds time and cost to the manufacturing of the proximity switch.